Replace CHANGELOG files by auto-generated "snapshot.commit"

Idea and implementation courtesy of Kim Phillips <kim.phillips@freescale.com>

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/snapshot.commit b/snapshot.commit
new file mode 100644
index 0000000..8d26309
--- /dev/null
+++ b/snapshot.commit
@@ -0,0 +1 @@
+$Format:%H  %cD$